Method of suppressing the oxidation characteristics of nickel

ABSTRACT

A method of providing a resistance to oxidation of Nickel at high temperatures by combining Ni powder with five percent Pt resinate, and heating the same to a temperature of 500° C. to 1300° C. Electro-conductive components serving as electrodes and the like comprise a Ni/Pt powder subjected to temperatures of between 500° C. and the respective melting points of Ni and Pt.

CROSS REFERENCE TO A RELATED APPLICATION

[0001] This application is based upon Provisional Application Serial No.______ filed Mar. 21, 2001.

BACKGROUND OF THE INVENTION

[0002] One of the major problems for using nickel (Ni) in an air firingceramic system in the capacitor industry is that this element willoxidize, before the ceramic components in the system have matured, toform a multilayer capacitor consisting of alternating layers of Ni asthe conductive plates to form a capacitor. This resultant Ni oxidationcan stress the capacitor during the heating cycle, which createsphysical defects, such as cracks in the ceramic body. One way toovercome this, which has become very well known in the industry is touse a ceramic capacitor system, which can be fired under an inert orreducing atmosphere, thus not allowing the Ni to oxidize through thethermal processing. Unfortunately, this requires the use of reductionresistant ceramics dielectric materials that are typically formulatedwith expensive high purity oxides and carbonates. Furthermore the firingprocess requires expensive kilns with very critical controls for gasflow.

[0003] It has been known in various literatures that platinum (Pt) hasthe capability to suppress oxidation on various metals. It has also beenknown that Pt suppresses the oxidation characteristics on palladium(Pd). Heretofore, Pt has not been used to suppress the oxidationcharacteristics of Ni.

[0004] It is therefore a principal object of this invention to provide amethod for suppressing the high temperature oxidation resistance of Nithrough the use of Pt.

[0005] A further object of the invention is to produce an alloy of Nipowder and Pt resinate wherein the two ingredients are heated to atemperature of between 500° C. and the respective melting points thereofto create an Ni/Pt alloy.

[0006] These and other objects will be apparent to those skilled in theart.

SUMMARY OF THE INVENTION

[0007] A method of providing a resistance to oxidation of Ni at hightemperatures by combining Ni powder with five percent Pt resinate, andheating the same to a temperature of 500° C. to the respective meltingpoints of Ni and Pt to create a Ni/Pt alloy. Electro-conductivecomponents serving as electrodes and the like comprise an Ni/Pt alloycreated by subjecting the above components to the above temperaturerange.

DESCRIPTION OF THE DRAWING

[0008]FIG. 1 is a graph showing the oxidation of Ni Powder (95%) mixedwith (5%) by weight of Pt and subjected to various concentrations ofheat.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0009] An experiment was conducted with coating a Ni powder using a Ptresinate. Ten grams of Ni powder and Pt resinate (liquid) which whenreduced to pure metal would be 5% of the total metal sample weight, weremilled in a glass jar with a 4 ZrO₂ media in alcohol. The sample wasdried and screened through a 100 mesh sieve. One gram of Ni/Pt powderwas mixed with one gram of electrode medium to form a paste, which waspainted onto an Al₂O₃ substrate.

[0010] The Al₂O₃ substrate, with the Ni/Pt sample painted thereon, washeat treated through a nitrogen atmosphere thick film firing furnace,using a 900° C. peak temperature profile, under the nitrogen atmosphereso that the sample would not oxidize during the cycle. The resultingNi/Pt alloy was then removed from the substrate and tested with theDTA/TGA along with the control Ni/Pt alloy, to measure it's oxidationresistance. No difference in the oxidation characteristic of the controlNi/Pt alloy and this quick heat treated alloy was seen.

[0011] It should be understood that the use of Pt resinate (a liquid)was used as a convenience. Pt powder in the same proportions can bemixed with Ni powder and then heat treated as described herein toachieve the same resulting alloy. Several samples of this Ni/Pt powderwere prepared in the manner described above and heat treated at variousdifferent temperature and time to determine if this system might requiremore heat energy to allow the Pt to alloy with the Ni. The heattreatment profiles were as follows: 500° C. for 4 hours, 1000° C. for 6hours and 1300° C. for 6 hours.

[0012] Each of the samples was heat treated in a high temperaturenitrogen and form gas capable furnace, in an atmosphere of forming gas(1% hydrogen, balance nitrogen). The samples were tested with theDTA/TGA for oxidation characteristics. (See FIG. 1).

[0013] The 500° C. heat treat sample clearly showed the Ni powderoxidation start point had shifted to 500° C. The oxidation point of the1000° C. heat treat samples shifted further to between 700° C. and 800°C. The 1300° C. heat treat samples performed even better, shifting theoxidation start point to over 1000° C. A repeat sample was prepared andheat treated at 1300° C. and it performed similar to the previous run.

[0014] It was determined that the resistance to oxidation of the Ni wasfavorable from 500° C. up to the melting points of Ni and Pt (which areapproximately 1453 and 1772° C., respectively).

[0015]FIG. 1 shows 5 curves on a graph which show the oxidation rate ofthe 95/5% mixture of Ni and Pt subjected to different temperatures. Theincrease in weight is caused by the additional weight of NiO produced bythe oxidation of the Ni.

[0016] This result has shown that Pt resinate mixed with Ni at 5% byweight of Pt resinate (or the same proportions of Ni and Pt powder),when heat treated properly is capable of suppressing the oxidationcharacteristics of Ni, so that it can function as air-fireableelectrode, with significant cost savings. (The resulting alloy from amixture of Ni and Pt resinate is comprised of Ni and Pt for the“resinate” is vaporized in the heating process.)

[0017] Aside from the capability for multilayer ceramic capacitorconductive plates or electrodes described above, other uses of the Ni/Ptcombination are possible: As an air-fireable end termination for anelectronic component which requires metallization to make the componentcircuit broad mountable as a SMT (Surface Mount Technology) product; oras a thick film screen printable air-fireable conductor material. Theproduction of the Ni/Pt alloy is the most significant aspect of thisinvention.

[0018] It is therefore seen that this invention will achieve its statedobjectives.

What is claimed is:
 1. An alloy comprised of Ni and Pt subjected to a heat treatment of between 500° C. to the melting point of Pt.
 2. The alloy of claim 1 wherein the alloy is produced by the heat treatment of Ni powder and Pt powder.
 3. The alloy of claim 1 wherein the Ni and Pt are present in the proportions of 95% to 5% by weight, respectively.
 4. The alloy of claim 2 wherein the Ni and Pt are present in the proportions of 95% to 5% by weight, respectively.
 5. An alloy comprised of Ni powder and a Pt resinate subjected to a heat treatment of between 500° C. to the respective melting points of the ingredients.
 6. A method of suppressing the oxidation characteristics of nickel, comprising, combining Ni with Pt in a ratio of approximately 95% Ni powder and 5% Pt by weight, and heat treating the Ni/Pt mixture to a temperature of between 500° C. and the melting point of Pt.
 7. The method of claim 6 wherein the heat treating takes place in a nitrogen atmosphere.
 8. The method of claim 6 wherein the heat treating atmosphere also comprises about 1% hydrogen.
 9. A method of creating an air-fireable and termination element for electronic components which requires metallization, comprising, making an air-fireable end termination element from a combination of Ni powder with Pt in a ratio of approximately 95% Ni powder and 5% Pt by weight, and heat treating the Ni/Pt mixture to a temperature of between 500° C. and the melting point of Pt.
 10. An air-fireable end termination element comprised of Ni and a Pt alloyed product heat treated to a temperature between 500° C. and the melting point of Pt.
 11. The device of claim 9 wherein the proportion by weight of Ni to Pt are approximately 95%-5%, respectively.
 12. An air-fireable conductor plate for capacitors comprised of Ni powder and Pt heat treated to a temperature between 500° C. and the melting point of Pt.
 13. The device of claim 12 wherein the proportion by weight of Ni to Pt is approximately 95%-5%, respectively.
 14. A thick film screen printable fireable conductor material comprised of Ni powder and Pt heat treated to a temperature between 500° C. and the melting point of Pt.
 15. The device of claim 14 wherein the proportion by weight of Ni to Pt are approximately 95%-5%, respectively.
 16. The method of making an alloy of Ni and Pt, comprising, combining Ni powder with Pt, subjecting the same to a temperature of 500° C. to the melting point of Pt, to create an alloy of Ni and Pt.
 17. The method of claim 16 wherein the Ni powder is mixed with the Pt in a ratio of 95-5%, respectively, by weight. 